Malfunction control system



March 1965 s. H. MACHLANSKI ETAL 3,171,250

MALF'UNCTION CONTROL SYSTEM 2 Sheets-Sheet I Filed Feb. 6, 1961 20:02 2.w m ozoowm ZEE-mm 22x0 55:8 5525 mm .L P 1: m2 SwwmEzou v a: 2. 13 3QmmwmEzoQ r mwfiexo ZV CARLE ATTOR Y United States Patent 3,171,250MALFUNCTION CONTROL SYSTEM Sigmund H. Machlanski, Yucaipa, and Carla C.Conway III, Fair Oaks, Calif., assignors to Aerojet-General Corporation,Azusa, Califl, a corporation of Ohio Filed Feb. 6, 1961, Ser. No. 87,16313 Slaims. (Cl. 6035.6)

This invention relates to a malfunction control for liquid fuel rocketmotors.

This application is a continuation-in-part of my copending applicationSerial Number 654,418, filed April 22, 1957, now abandoned.

Rocket motors require very carefully designated control systems becauseof the extremely high energy developed by the fuel, and the number ofcomponents, all of which must operate within close limits to insureproper functioning of the motor, and the faulty operation of some ofwhich elements may cause a violent explosion. A faulty operation isinstantly detected and if the failure is remedied or the motor shut downsafely, damage to the motor may be avoided.

When starting and stopping a liquid fuel rocket engine, a sequence ofoperations is required; the duration of which has been carefullycalculated, although the time interval of some may be only somethousandth of a second.

Before this invention, the operation of the various engine components inthe manner required was usually effected by electrical means withelaborate interlocks, various relays, time delays, and other componentsresulting in complicated and expensive systems. These components couldeasily get out of adjustment, provide only intermittent control andtheir operation requires skilled technicians.

A major danger to be considered during the starting and functioning ofliquid fuel rocket engines is possible accumulation of unburnt fuel inthe thrust chamber. These conditions are evidenced by an absence orsudden loss of pressure in the combustion chamber and require,substantially instantaneous closing of the fuel and/or oxidizer ejectionvalves to prevent further hazardous propellant injection.

In addition, a number of other safeguards are desirable in starting themotor in case all auxiliary functions for proper operations are notperforming satisfactorily, and similarly to guard against malfunctionsin shutting down the motor.

The control mechanism must be very sensitive, function with extremerapidity, necessitating very small but accurate control movements ofsome mechanical parts, and be capable of withstanding and transmittinghigh stresses and intense vibration.

The malfunction control of the present invention is specificallyconcerned with the control of the combustion chamber injection platevalve means which governs the flow of fuel to the combustion chamber.The basic feature of the invention resides in a computing device, perse, which may be incorporated in various control systems and inconjunction with various subsidiary or auxiliary mechanisms to insuresafe functioning of a rocket motor from starting to shut down, includingrepeated firings.

It is the primary object of the invention to provide a continuous directsensing means operating to maintain direct control of fuel flow rateinto a thrust chamber in relation to the fuel flow rate out of a thrustchamber.

A further object of the invention is to provide a malfunction controloperative to terminate the rocket engine operation in the event that thefuel flow rate drops below a predetermined critical value.

For these and other objects in view, the invention comprises a computingdevice which continuously compares 3,171,250 Patented Mar. 2, 1965 thefuel flow rate into a combustion chamber with the fuel flow rate,exhausted from the combustion chamber, and controls a fuel injectorplate valve means which regulates the flow of fuel into the combustionchamber. The preselected values of flow rates are set sufficiently belowdesigned operating efficiency to allow for normal performance variationsdue to system tolerances.

Still further features and objects of the invention will hereinafterappear from the following specification and the accompanying drawings ofa preferred embodiment of the invention.

In the drawings:

FIGURE 1 is a schematic diagram showing the environment of the automaticcombustion chamber control device in a liquid fuel rocket engine; and,

FIGURE 2 is a schematic diagram of the automatic combustion chambercontrol device.

Referring now to FIGURE 1 of the drawing, the fuel inlet line 1 leads toa pump P that discharges the fuel under pressure through line 2 andcheck valve 2d. Part of the fuel is conducted by branch line 3 to theinjector plate valve 4 (FIGURE 2) arranged in an injector plate 4a andthe primary chamber 412. The remainder of the fuel is conducted throughline 5 and secondary injection valve 6a to the secondary thrust chamber6. The oxidizer is conducted through line 7 to pump P and is thendelivered under pressure through line 8 and check valve 8d to the coolerpassages 8b surrounding the combustion chamber nozzle and then throughinlet to the oxidizer manifold 9 (FIGURE 2). The manifold 9 surroundsthe fuel inlet valve 4 in the injector plate 4a and from the manifold 9,the oxidizer is injected through oxidizer valves 10 surrounding the fuelinlet valve 4. Pumps P and P are driven by a turbine indicated by thelegend turbine which in turn is driven by hot pressurized gas broughtfrom chamber 4b through the conduit indicated by the legend turbineline.

The engine is put into operation by fuel and oxidizer delivered fromstarter pumps 2a and 8a operated by air under pressure from any suitablesource (not shown) through the line indicated by the legend compressedair and valve 82. The pressurized fuel and oxidizer is transmittedthrough the starter valves 11b and operated by piston or servo-motor11d, which is controlled by valve 11c, and also to the starter chamber11 in which ignition is effected by glow plug 11a.

The pressure generated in the starter chamber 11 is led by conduit 50ato the malfunction control unit C to permit opening of the primaryinjection valve of the engine by a pilot valve 13. The burning gasesfrom the starter chamber are injected through conduit 12 into thecombustion chamber to ignite the propellant injected therein.

Referring to FIGURE 2, the pilot valve 13 is provided with an adjustablelimit stop 14 to control opening of the injection plate valve 4 at apredetermined maximum rate by control of the rate of flow of fuel. Thevalve 13 is provided with an operating rod 15 which is controlled by thecomputing device. Fuel is supplied to the pilot valve 13 through pipe 16from fuel line 2 and branch line 3a, the fuel flowing through the valve13 and pipe 17 through the coil spring 25a in the rapid shut down valve23 and through pipe 24 to the actuator cylinder 18 controlling the fueland oxidizer valves 4 and 10 in the injection plate 4a.

A piston 19 is arranged in the cylinder 18 and is urged by a spring 20toward valve closing position. The piston 19 is mounted on a rod 21 onwhich is secured a yoke 22 operating simultaneously all the pintles ofthe injector valves 4 and 10. The pressurized fuel from pipe 24 admittedto the cylinder 18 acts against spring 20.

Normal ignition will resolve in continued maintenance of pilot valve 13at the full open position due to the operation of the control unit C.Therefore the operating yoke 22 continues opening the valves 4 and atthe associated control rate to the full open position. The combustionchamber operating pressure bllilds up to design level as the fuel flowincreases. The turbo pumps come up to speed and take over the fuel andoxidizer supply from the starter pumps thus maintaining design or normaloperation. In the event that a combustion malfunction takes place duringany of this operation, the malfunction system becomes operative.

The rapid shut down valve 23 is placed in communication with the fuelspace in the cylinder 18 by pipe 24. The valve 23 is formed as acylinder containing a hollow piston which is urged toward closedposition by coil spring 25a. Fuel flow toward the cylinder 18 creates apressure drop across the restricted passage 23a through piston 25' whichalso urges the piston 25 toward the closed position. Reversal of fuelflow away from cylinder 18 on closing of pilot valve 13 creates apressure drop across passage 23a which opposes spring 25a and urgespiston 25 open. Opening motion of piston 25 permits flow from cylinder18 to enter chamber 23b. The pressure force balance on piston 25 isimmediately changed by virtue of the fuel pressure increase in chamber23b which increases the opening force creating rapid motion to theexhaust position of valve 23. The main portion of the fuel from cylinder18 is then ported directly to line 29 causing rapid venting of cylinder18 and therefore effecting closure of the injector valves 4 and 10 byaction of spring 20.

A three way valve 31 controls the admission of fuel under pressure tothe malfunction control device. The normal operating position of valve31 as shown in FIG- URE 2 allows fuel to pass through line 2, line 3a,line 16, and line 35. In this position, pilot valve 13, rapid shut downvalve 23, actuator cylinder 18, and actuator 32 are all supplied withfuel pressure. Voluntary shut down of the entire system may be effectedby rotating the valve 31 to a position 90 clockwise of that shown inFIGURE 2. In this shut down postion, the fuel flow from line 2 to line3a is terminated and the flow path is opened between line 3a and line(drain line). Therefore, the pilot valve 13, rapid shut down valve 23,actuator cylinder 18, and actuator 32 are all open to drain allowing thespring biased pistons to close. In this manner, the piston 19, under theaction of spring 20, doses (moves to the right in FIGURE 2) therebymoving yoke 22 and closing the injector plate valves 4 and 10.

A command shut down actuator 32 insures that the computer cannot effectopening of the injector valves 4 and 10 until a minimum fuel pressure isattained by the action of the starter pumps 2a and 8a. The actuator 32is formed as a cylinder33 containing a piston 34 moved in one directionby fuel introduced into the cylinder through a pipe 35 and urged in theopposite direction by spring 36. The piston 34 is mounted on a rod 37extending through both ends of the cylinder and bearing with one endagainst the computing mechanism. The opposite end of the rod 37 isprovided with a collar 38 adapted to reset a pivoted override lever 39.

The override lever 39 is operated with snap action by means of a spring40 moving over center and a follower pin 41 riding on the surface ofpiston rod 21. The lever 39 is engaged by collar 42 on the rod 21 whenthe injector valves 4 and 10 are moved to an open position by movementof piston 19. As lever 39 is moved to the opposite or reset direction,the command shut down actuator 32 causes the malfunction device to closethe injection valves 4 and 10 by engagement of a tail 43 of the lever 39that is engaged by the collar 38 on the rod 37.

The override lever 39 is adapted to strike an override pin 44 slidablein the fixed structure 45 and engaged against one end of the small lever46 pivoted to the fixed structure. The other end of the lever 46 engagesthe disc 47 that is secured to the rod 48 yieldly and axially connectedto the rod 49 mounted on a bellows 50. Pressure is set intothe bellows50 from the starter chamber 11 through the pipe 50a. The force generatedby the starter chamber pressure is reduced by the system of springs andis applied to lever 54 through rod 48 by spring 51. The reduction inforce, designed to render the high starter chamber pressure(approximately 250 p.s.i.) equivalent to a combustion chamber pressureinput of 80 p.s.i. at bellows 70, is achieved by absorbing most of theforce generated by bellows 50 in the spring 52 which bears against theend plate of the bellows 50 and against the fixed structure. The balanceof the force is transmitted through rod 49 to spring 51 and thereafterto rod 48. The computer device incorporated in the malfunction controlsystem comprises a forced balance lever 54 pivoted at 55 on fixedstructure 56. Lever 54 is engaged at one side of the pivot 55 by rod 48and on the opposite side from rod 48 by rod 57, transmitting thedifferential fuel pressure of opposed bellows 58. Section 59 of theopposed bellows 58 receives pressure through pipe 60 from the combustionchamber and the other section 61 of the bellows receives fuel linepressure through pipe 62. The finger 63 transmits the differentialpressure force through a spring 64 through rod 57, and throughcantilever spring 65 to the fixed structure.

One end of cantilever spring 65 is secured in fixed structure 66. Thedeflection rate of spring 65 is modified by a series of stops 67 ofdecreasing height from the anchored end of spring 65. By propercalibration of these stops 67, the force input through shaft 57 is madea logarithmic function of the force at finger 63, or the logarithm offorce exerted by finger 63 is equal to the force transmitted through rod57.

The force transmitted to the short end 68 of rod 54 of the doublebellows is therefore a logarithmic function of the differential pressure(P -P where P; equals yield supply pressure, and P equals combustionchamber pressure.

On the opposite side of pivot 55, but on the same side i of the lever 54as rod 57, a bellows 70 is positioned and receives pressure through pipe71 from the combustion chamber. The pressure developed in this bellows70 is converted logarithmically and applied to balance lever 54 in amanner similar to that described for the opposed bellows 58. Thepressure is transmitted by the bellows '70 to a cantilever spring 72,one end of which is mounted on a fixed structure 73. The spring 72 isconstrained to follow a logarithmic deflection in a manner similar tothat described for spring 65. The resulting movement of the bellows 70is transmitted through a spring '74 to a rod acting against a forcedlever 54 at an equal distance from pivot 55 and in a direction whichopposes the force exerted by rod 57. Both springs 64 and 74 deliverlinear thrust against lever 54 but spring 74 is designed to be twice asstiff as spring 64 for reasons which will later appear. Lever 54 isengaged on the side opposite to rod 75 by rod 76 receiving the thrust ofpiston rod 21 through a spring 77 arranged between a disc 78 secured onpiston rod 21 and a disc '79 integral with rod 76. The purpose of thisspring is to transform the movement of the piston rod 21 into a forceacting against the lever.

The purpose of inter-posing springs 64 and 74 between the respectiveforce producing elements and lever 54 is to transform the logarithmicdisplacement of springs 65 and 72 to a logarithmic force by the linearreactions of the springs.

The force lever 54 is extended beyond the point of engagement of rods75, 76 therewith, providing a longer arm 69 which is engaged by rod 37.The end of operata ing rod 15 is pivotally attached to the end of arm69.

It is the purpose of the computer mechanism to compare the ratio of thepropellant flow rate passing through and out of the combustion chamberto the propellant flow rate passing into the combustion chamber, and tooperate a pilot valve controlling the actuation of the propellantinjection valve in accordance with variations of the ratio. The computermechanism will then take appropriate action when the flow rate enteringthe chamber exceeds the rate going out of the chamber. The termsselected in this case to represent these two parameters of flow rates,i.e. the combustion rate and the propellant flow rate, are respectively,the product of the effective flow rate through the fuel inlet valve 4and the square root of the fuel pressure drop from the fuel valve 4 tothe combustion chamber which may be expressed as L w PiP. where P equalsactual combustion chamber pressure; A equals effective area of the fuelflow through valve 4 to the combustion chamber in square inches; Pequals fuel supply pressure in p.s.i.a.; and K equals a predeterminedcritical value of the ratio. The purpose of taking the square root of (PP is that flow through an orifice varies as the square root of thepressure drop. The problem may be solved by dealing with thecorresponding logarithmic form of the equation which is log P log A,+ /2log (P -P The motion of the injector plate valve operating shaft 21 isdirectly applied to the force balance lever 54 through a linear spring77. The variation in flow area is made a logarithmic function of strokeby the contour of the injector plate valves 4 and 19. The conversion ofthe pressure forces from the linear functions obtained by the pressurebellows to a logarithmic function at the force balance lever 54 isaccomplished by the cantilever springs 65 and '72, as described.

It may be seen that the operation of the computer so far described wouldnot permit the starting of the rocket motor since this requires that thefuel be injected prior to the combustion and establishment of thecorresponding combustion chamber pressure. The amount of fuel which maybe safely injected prior to ignition is a very small quantity whichtherefore must be metered with extreme precision. An additionalmechanism may be integrated with the computer mechanism to achieve thisprecise metering of the ignition flow. This mechanism is shown in FiGURE2 and comprises a starter chamber pressure bellows 5G and force reducingsprings 52 and 51, the over-center spring acting lever 39 andtransmitting linkage lever 46 and pressure rod lever 44. The presence ofstarter chamber pressure at the required level in bellows 5% establishesthe fact that a satisfactory source of ignition is present in thecombustion chamber 41;. This pressure force is reduced by springs 52 and51, to an input force at rod 48 winch corresponds to chamber pressure.This apparent main chamber pressure satisfies the conditioncorresponding to direct functioning and permits openin of the maininjector valves 4 and When the valves reach the position at whichignition should have taken place, the collar 42 strikes pin 41 drivinglever 3% over-center whereupon spring 49 exerts sufficient force throughrod 44 and lever 46 to lift spring 51 and remove the starter chamberpressure force from shaft 48. A satisfactory chamber pressure must nowexist at bellows 70 to replace the starter pressure input or else thecomputer will signal a complete shut down. It will be noted that theoperation of the malfunction control described and illustrated includesa computing device which is fully automatic in operation and thereforeindependent of manual control.

Operation All operation and mechanism functions pertinent to thisspecification have now been described. To aid in understanding theinterrelation of these operations and functions a typical operatingsequence is outlined.

At the commencement of operation the starter pumps in and 8a supplypressurized fuel and oxidizer to the injector plate valves 4 and It thesecondary injector Valve 6a, the starter chamber 11 and through thethreeway control valve 31 to the malfunction control device C. A starterchamber 11 has been placed in operation by conventional valving andignition means. At this point, the malfunction control device C willbegin operation of the combustion chamber by permitting the injectorplate valves 4 and 10 to open only if the following conditions arecontinued to be met;

1) Sufficient fuel pressure is present at the injector plate valves tomeet designed requirements. This is determined by the command shut downactuator 32 which moves the pilot valve through the medium of the lever54 into the shut down position unless the fuel pressure is above theminimum requirement. Fuel pressures above the minimum urge piston 34against spring 36 overcoming the preset force and thereby releasing thelever 54.

(2) An adequate ignition source at the main chamber is established. Theignition source is the exhaust gas from the starter chamber 11. Adequatesupply of hot gases is evidenced by the sufficiently high level ofstarter chamber pressure. This is determined by the control device bytransmitting this pressure input through bellows 50 and springs 52 and51. The preset calibration of this mechanism insures that starterchamber pressure will be above the required minimum before the lever 54will pivot from the shut down to the open position.

Assuming these necessary conditions are met, the injector plate valves 4and Ill begin opening at a rate controiled by the adjustment of stop 14located in pilot valve 13. At the position of lever 54 corresponding tothe non-ignition detection point, the upper right lever 46 is snappedagainst the spring 51, lifting it and thereby uncoupling the starterchamber pressure input from lever 54. In order to maintain the pilotvalve 13 at the open position adequate combustion chamber pressure mustbe present at the bellows 70.

Assuming for the moment that normal operation exists, the main injectionvalves 4 and 10 would reach the full open position and the entire enginewould be operating under the proper fuel pressure and combustion chamberpressure. Normal operation as far as the present invention is concerned,means the operation of the rocket engine while it is supplied with fuelsuch that the combustion pressure corresponds to the fuel flow ratewhich occurs as a result of complete combustion of all the fuel. Thissystem is designed to react to abnormal operation, which is a loss ofcombustion pressure without a corresponding drop in fuel flow rate. Thesystem insures that the minimum value of fuel pressure and combustionchamber pressure is reached before the lever 54 will balance and thatloss of either pressure in excess of the low and design limit willimmediately shut down the engine. Auxiliary devices such as the starterchamber 11 and starter pumps 2a and 8a are cut out of the operation inaccordance with the engine operating sequence. This operation is notdirectly involved with the operation of the present invention. Atcompletion of the normal run command, command shut down is effected bymoving valve 31 to the position clockwise of the position shown onFIGURE 2 thereby terminating the supply of fuel pressure and venting thefuel pressure through pipe 30 to the pump P It will be noted that thisis identical to the condition which is automatically generated in theevent of loss of fuel pressure and the control device reaction is thesame in both cases. The

command shut down generator 32 is urged by spring 36 to overpower thebalance force system on lever 54 and drive pilot valve 13 to the closingposition as well as resetting override lever 39. The rapid shut downsequence involving valve 23 is generated by the displacement of pilotvalve 13 as has been fully described previously. The injector platevalves 4 and are rapidly closed by this sequence and by the specifiedmechanism. The control system is seen, therefore, to be automaticallyreset and ready for restart immediately after completion of a shut down.

The operation just described represents a normal run. At any point inthe operation, loss of the fuel pressure would precipitate the samerapid shut down sequence by unbalancing lever 54 to move pilot valve 13to the closed position.

It is pointed out that while a complete operative malfunction device hasbeen described, certain elements other than the computing device itselfmay be replaced by other means.

For instance, the means for initially placing the computer in operationby pressure from the starter chamber may be replaced by other meanswhich automatically cut out after starting. Also, the command shut downactuator 32 and the rapid opening valve 23 are not necessary componentsof the computer control device in its basic configuration. Theparticular arrangement of the injector plate valves for computing flowmight be replaced by a valve of standard arrangement in conjunction witha flow meter of suitable design with suitable arrangement of computerelements. Furthermore, the employment of conditions sensitive mechanismsuch as the starter chamber pressure input and the fuel pressuresensitive shut down actuator may be extended to include an unlimitednumber of devices of similar nature to determine the existence of allnecessary or desired operating conditions, and to preclude operation ifany condition is violated.

While the preferred embodiment of the invention has been specificallydescribed and illustrated in the accompanying drawings, it is to beunderstood that the illustrated embodiment is not limitative of theinvention since various modifications may be made therein by thoseskilled in the art without departing from the scope of the invention asdefined by the appended claims.

We claim:

1. A control device in combination with a thrust chamber comprising: asource of fuel, conduit means communicating with said fuel source andsaid thrust chamber, a first means communicating with the thrust chamberfor detecting the fuel fiow rate into the said thrust chamber, a secondmeans communicating with the thrust chamber for detecting the fuel flowrate from the thrust chamber, a pilot valve interposed in said fuelconduit means, a means for regulating fuel flow into said thrust chamberand a means for opening and closing the said pilot valve operated by thefirst and second fuel flow detecting means whereby the pilot valve maybe closed when the fuel flow into the thrust chamber exceeds the fuelflow from the thrust chamber which operates to close the fuel fiowregulating means.

2. A control device in combination with a thrust chamber as defined inclaim 1 in which the fuel flow regulating means comprises: and injectorplate valve having movable injectors therein and received by the saidthrust chamber, a resiliently biased piston having a first and a secondside contained in a closedcylinder, said injector plate valve injectorsfixedly attached to the first side of the said piston, said fuel conduitmeans being attached to the closed cylinder and directed toward thefirst side of the said piston, and said piston being resilientlyattached to the said means for closing the said pilot valve regulated bythe first and second fuel fiow detecting means whereby said piston willregulate said injector plate valve in relation to fuel flow.

3. A control device in combination with a thrust chamber comprising: afuel source, a first conduit attached between the said thrust chamberand said fuel source, a lever having a first and second side, a pivothaving a first and a second side supporting the said lever, a firstelement resiliently contacting the first side of the said lever, a firstcollapsible pipe attached between the said thrust chamber and the saidfirst element urging the said first element out of contact with the saidlever, a second collapsible pipe attached between the fuel source andthe said first element urging the said first element against the saidlever, a second resiliently biased element in contact with the leverpositioned on the second side of the said pivot and on the first side ofthe said lever, a third collapsible pipe attached to the said secondelement and the thrust chamber tending to urge the second elementagainst the lever, a third resiliently biased element touching the saidlever directly opposite the said second element, a resiliently biasedpiston attached to the said third element, a cylinder enclosing the saidpiston, a means for regulating fuel to the thrust chamber attached tothe said piston, a pilot valve, a rod attached between the said pilotvalve and the said lever, a second conduit attached to the said fuelsource and the said cylinder carrying a fuel under pressure, thepressure of said fuel acting to urge the said rod against the said leverand the said third element against the said lever, said pilot valveinterposed in said second conduit between said cylinder and said fuelsource, whereby a drop in fuel pressure or thrust chamber pressurecauses the fuel regulating means to cut olf fuel flow into the thrustchamber.

4. A control device in combination with the thrust chamber as defined inclaim 3 and in addition a rapid shut down valve interposed in saidsecond conduit and positioned between the said pilot valve and the saidcylinder.

5. A control device in combination with a thrust chamber as defined inclaim 3 in which the said first and second elements are positionedequidistant on opposite sides of the pivot for the lever.

6. A control device in combination with a thrust chamber as defined inclaim 3 in which the said fuel regulating means is a fuel injector,

7. A control device in combination with a thrust chamber comprising: afuel source, a first conduit connected between the fuel source and thethrust chamber, a balance member having a first and second side, a firstresiliently biased rod contacting the first side of the balance member,a first bellows contacting said first rod and urging said first rodtoward the first side of the balance member, a second conduit connectedbetween the fuel source and the said first bellows, a second bellows contacting the said first rod positioned opposite the first bellows andurging the said first rod out of contact with the balance member, asecond conduit connected between the said second bellows and the thrustchamber, a second resiliently biased rod contacting the first side ofthe balance member and positioned in spaced relation with the said firstrod, a third bellows contacting the said second rod and urging saidsecond rod toward the said balance member, a third conduit connectedbetween the thrust chamber and the third bellows, a third resilientlybiased rod contacting the second side of the balance member andpositioned directly opposite the said second rod, a resiliently biasedpiston attached to the said third rod, a closed cylinder enclosing thesaid piston, 21 means for regulating the fuel flow received by the saidthrust chamber and attached to the said piston, a fourth conduitinterconnected between the fuel source and the cylinder, 2) pilot valveinterposed in the fourth conduit and positioned between the fuel sourceand the said cylinder, and an operating rod attached to the pilot valveand to the said balance member, whereby a loss of fuel pressure orthrust chamber pressure will cause a change in position of the balancemember thereby causing the pilot valve to cut fuel fiow to the cylinderand cause the fuel regulating means to terminate fuel fiow into thethrust chamber.

8. A control device in combination with a thrust chamber as defined inclaim 7 and in addition a rapid shut down valve interposed in the saidsecond conduit and positioned between the said pilot valve and the saidcylinder.

9. A control device in combination with a thrust chamber as defined inclaim 7, further including a pivot supporting said balance membermedially of the ends thereof, and the said first and second rod beingpositioned equidistant on opposite sides of the pivot for the balancemember.

10. A control device in combination with a thrust chamber as defined inclaim 7 in which the said fuel regulating means is a fuel injector.

11. A control device in combination with a thrust chamber comprising: asource of fuel, conduit means communicating between the fuel source andthrust chamber, a first means communicating with the conduit means fordetecting fuel flow rate into the thrust chamber, a second meanscommunicating with the thrust chamber for detecting the fuel flow ratefrom the thrust chamber, a means associated with the thrust chamber forregulating fuel flow into the said thrust chamber, and a means attachedto the fuel regulating means for comparing the fuel flow rate into thethrust chamber with the fuel flow rate out of the thrust chamber, saidcomparing means actuating said fuel regulating means to reduce the fuelflow rate into the thrust chamber when the fuel flow rate into thethrust chamber exceeds the fuel flow rate from the thrust chamber.

12. A control system for a rocket motor thrust chamber fueled by a fluidpropellant source comprising: conduit means adapted to interconnect saidthrust chamber and said fluid propellant source; first means fordetecting the rate of propellant flow into said thrust chamber; secondmeans for detecting the rate of gas flow out of said thrust chamber;means for regulating propellant flow into said thrust chamber, saidregulating means being serially connected in the propellant flow pathformed by said propellant source, said conduit means and said thrustchamber; a pilot valve interposed in said conduit means, said pilotvalve being operatively connected with said regulating means; and meansfor actuating said pilot valve, said actuating means being associatedwith said first and second flow detecting means; said first and seconddetecting means energizing said actuating means to cause said pilotvalve to operate to close said propellant regulating means when thepropellant flow rate into the thrust chamber exceeds a magnitude forminga predetermined ratio with the gas flow rate from said thrust chamber.

13. A control device in combination with a thrust chamber comprising: asource of fuel, conduit means communicating between the fuel source andthe thrust chamber; a first means for detecting fuel flow rate into thethrust chamber, the first detecting means communicating with the conduitmeans, and the first detecting means generating an output force which isproportional to the fuel flow rate into the thrust chamber; a secondmeans for detecting fuel flow rate from the thrust chamber, the seconddetecting means communicating With the thrust chamber, and the seconddetecting means generating an output force which proportional to thefuel flow rate from the thrust chamber; means associated with the thrustchamber for regulating fuel flow into the thrust chamber, and meansattached to the fuel regulating means for comparing the output forcesexerted by the first and second detection means; whereby an excess offuel flow rate into the thrust chamber in relation to the fuel flow rateout of the thrust chamber above a predetermined ratio will cause thecomparison means to close the fuel flow regulation means.

References Cited in the file of this patent UNITED STATES PATENTS2,724,239 Fox Nov. 22, 1955 2,761,282 Allen Sept. 4, 1956 2,779,158Dungan Jan. 29, 1957 2,897,649 Reddy Aug. 4, 1959 2,995,008 Fox Aug. 8,1961 3,069,849 Crim Dec. 25, 1962 FOREIGN PATENTS 1,017,707 France Dec.18, 1952

1. A CONTROL DEVICE IN COMBINATION WITH A THRUST CHAMBER COMPRISING; ASOURCE OF FUEL, CONDUIT MEANS COMMUNICATING WITH SAID FUEL SOURCE ANDSAID THRUST CHAMBER, A FIRST MEANS COMMUNICATING WITH THE THRUST CHAMBERFOR DETECTING THE FUEL FLOW RATE INTO THE SAID THRUST CHAMBER, A SECONDMEANS COMMUNICATING WITH THE THRUST CHAMBER FOR DETECTING THE FUEL FLOWRATE FROM THE THRUST CHAMBER, A PILOT VALVE INTERPOSED IN SAID FUELCONDUIT MEANS, A MEANS FOR REGULATING FUEL FLOW INTO SAID THRUST CHAMBERAND A MEANS FOR OPENING AND CLOSING THE SAID PILOT VALVE OPERATED BY THEFIRST AND SECOND FUEL FLOW DETECTING MEANS WHEREBY THE PILOT VALVE MAYBE CLOSED WHEN THE FUEL FLOW INTO THE THRUST CHAMBER EXCEEDS THE FUELFLOW FROM THE THRUST CHAMBER WHICH OPERATES TO CLOSE THE FUEL FLOWREGULATING MEANS.